Dear Vilas,
Firstly i would suggest you put in your product description that the customer has to check the contents of the package with the presense of the courier guy, once he/she sees everything is fine, then sign for the courier, if there is a discrepancy in the package please do not accept the package... once the package is accepted we cannot take any responsibility.
This is the best you can do because ebay does not care about scenarios and go blindly with some vague policies which is really unfair and all the policies are very subjective. Moreover they just put the blame only on sellers and do not accept any mistake on their side.... there is no use of me or you cribbing about ebay, i do not have that time and interest to sue ebay... otherwise i would.....
Hope i answered your query,
Subash